Cryptology ePrint Archive: Report 2005/273

CRYPTOGRAPHY BASED ON CHAOTIC SYNCHRONIZATION: ROUND III

P G Vaidya and Sajini Anand

Abstract: This paper discusses cryptography based on the property of chaotic
synchronization. Specifically, it is about Round III of such a
cryptographic method. Round I showed the feasibility of using
chaotic synchronization for cryptography. Round II consisted of a
method to counter attack. This paper is Round III and shows how to
counter the counter attacks. First, we show numerical evidence that
synchronization is possible between two Lorenz systems if one system
sends information about $x_0$ at a slower rate. The second system
evolves on its own, except that when it receives a signal from the
first system, it replaces its own value of $y_0$ by the received
$x_0$. We have found that the two systems eventually synchronize,
but often after a long time. Therefore, we have devised a technique
to speed-up this synchronization. Once this is done, it is possible
for the authorized receiver (with the possession of the initial
super-key) to keep synchronizing with slowly sampled inputs, whereas
the known methods of Round II do not help an eavesdropper.